tree.hpp

/*********************************************************************
 *
 * Linear Arrangement Library - A library that implements a collection
 * algorithms for linear arrangments of graphs.
 *
 * Copyright (C) 2019 - 2023
 *
 * This file is part of Linear Arrangement Library. The full code is available
 * at:
 *      https://github.com/LAL-project/linear-arrangement-library.git
 *
 * Linear Arrangement Library is free software: you can redistribute it
 * and/or modify it under the terms of the GNU Affero General Public License
 * as published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * Linear Arrangement Library is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Linear Arrangement Library.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Contact:
 *
 *     Lluís Alemany Puig (lalemany@cs.upc.edu)
 *         LARCA (Laboratory for Relational Algorithmics, Complexity and Learning)
 *         CQL (Complexity and Quantitative Linguistics Lab)
 *         Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *         Webpage: https://cqllab.upc.edu/people/lalemany/
 *
 *     Ramon Ferrer i Cancho (rferrericancho@cs.upc.edu)
 *         LARCA (Laboratory for Relational Algorithmics, Complexity and Learning)
 *         CQL (Complexity and Quantitative Linguistics Lab)
 *         Office S124, Omega building
 *         Jordi Girona St 1-3, Campus Nord UPC, 08034 Barcelona.   CATALONIA, SPAIN
 *         Webpage: https://cqllab.upc.edu/people/rferrericancho/
 *
 ********************************************************************/
 
#pragma once
 
// C++ includes
#if defined DEBUG
#include <cassert>
#endif
#include <vector>
#include <array>
#include <string>
 
// lal includes
#include <lal/graphs/graph.hpp>
#include <lal/graphs/tree_type.hpp>
 
namespace lal {
namespace graphs {
 
class tree : virtual public graph {
public:
    /* CONSTRUCTORS */
 
    tree() noexcept { }
    tree(const tree& t) noexcept : graph() {
        tree_only_copy(t);
    }
 
    tree(tree&& t) noexcept {
        tree_only_move(std::move(t));
    }
 
    virtual ~tree() noexcept { }
 
    /* OPERATORS */
 
    tree& operator= (const tree& t) noexcept {
        tree_only_copy(t);
        return *this;
    }
    tree& operator= (tree&& t) noexcept {
        tree_only_move(std::move(t));
        return *this;
    }
 
    /* MODIFIERS */
 
    virtual void calculate_tree_type() noexcept = 0;
 
    /* GETTERS */
 
    bool is_tree() const noexcept {
        // NOTE: this would not really be true if the addition of edges
        // was not constrained. Since it is, in a way that no cycles can
        // be produced, then we only need to check for the number of edges.
        return (get_num_nodes() == 0 ? true : get_num_edges() == get_num_nodes() - 1);
 
        // NOTE 2: this is only true in a debug compilation of the library
        // since a release compilation does not actually constrain the addition
        // of edges
    }
 
    virtual bool is_rooted() const noexcept = 0;
 
    virtual bool can_add_edge(node s, node t) const noexcept;
 
    virtual bool can_add_edges(const std::vector<edge>& edges) const noexcept;
 
    uint64_t get_component_representative(node u) const noexcept {
#if defined DEBUG
        assert(has_node(u));
#endif
        return m_root_of[u];
    }
 
    bool are_nodes_in_same_component(node u, node v) const noexcept {
        return get_component_representative(u) == get_component_representative(v);
    }
 
    uint64_t get_num_nodes_component(node u) const noexcept {
#if defined DEBUG
        assert(has_node(u));
#endif
        return m_root_size[m_root_of[u]];
    }
 
    bool is_of_tree_type(const tree_type& tt) const noexcept {
        return m_tree_type[static_cast<std::size_t>(tt)];
    }
 
    bool is_tree_type_valid() const noexcept { return m_is_tree_type_valid; }
 
    std::vector<std::string> get_tree_type_list() const noexcept;
 
protected:
    std::vector<node> m_root_of;
    std::vector<uint64_t> m_root_size;
 
    std::array<bool,__tree_type_size> m_tree_type;
    bool m_is_tree_type_valid = false;
 
protected:
    void tree_only_init(uint64_t n) noexcept {
        m_root_of = std::vector<uint64_t>(n);
        m_root_size = std::vector<uint64_t>(n);
        for (node u = 0; u < n; ++u) {
            m_root_of[u] = u;
            m_root_size[u] = 1;
        }
        std::fill(m_tree_type.begin(), m_tree_type.end() - 1, false);
        m_is_tree_type_valid = false;
        m_tree_type[static_cast<std::size_t>(tree_type::unknown)] = true;
    }
    void tree_only_clear() noexcept {
        m_root_of.clear();
        m_root_size.clear();
        std::fill(m_tree_type.begin(), m_tree_type.end() - 1, false);
        m_is_tree_type_valid = false;
        m_tree_type[static_cast<std::size_t>(tree_type::unknown)] = true;
    }
 
    void tree_only_copy(const tree& t) noexcept {
        // copy this class' members
        m_root_of = t.m_root_of;
        m_root_size = t.m_root_size;
        m_is_tree_type_valid = t.m_is_tree_type_valid;
        m_tree_type = t.m_tree_type;
    }
    void tree_only_move(tree&& t) noexcept {
        // move this class' members
        m_root_of = std::move(t.m_root_of);
        m_root_size = std::move(t.m_root_size);
        m_is_tree_type_valid = t.m_is_tree_type_valid;
        m_tree_type = std::move(t.m_tree_type);
 
        t.m_is_tree_type_valid = false;
    }
 
    void actions_after_remove_node(node u) noexcept;
    void actions_after_add_edge(node u, node v) noexcept;
    void actions_after_remove_edge(node u, node v) noexcept;
    void actions_before_remove_edges_incident_to(node u) noexcept;
 
    void tree_only_set_edges() noexcept;
 
    void tree_only_remove_node(node u) noexcept;
 
    void fill_union_find() noexcept {
        for (node u = 0; u < get_num_nodes(); ++u) {
            // all vertices point to root zero
            m_root_of[u] = 0;
        }
        // the size of the connected component of the root 0 is n
        m_root_size[0] = get_num_nodes();
    }
 
    virtual void update_union_find_after_edge_add(
        node u, node v,
        uint64_t * const root_of, uint64_t * const root_size
    ) noexcept = 0;
    virtual void update_union_find_after_edge_add(
        node u, node v,
        uint64_t * const root_of, uint64_t * const root_size
    ) const noexcept = 0;
 
    virtual void update_union_find_after_edge_remove(
        node u, node v,
        uint64_t * const root_of, uint64_t * const root_size
    ) noexcept = 0;
    virtual void update_union_find_after_edge_remove(
        node u, node v,
        uint64_t * const root_of, uint64_t * const root_size
    ) const noexcept = 0;
 
    virtual void update_union_find_before_incident_edges_removed(
        node u,
        uint64_t * const root_of, uint64_t * const root_size
    ) noexcept = 0;
    virtual void update_union_find_before_incident_edges_removed(
        node u,
        uint64_t * const root_of, uint64_t * const root_size
    ) const noexcept = 0;
};
 
} // -- namespace graphs
} // -- namespace lal